Hydrological research on snowmelt processes in both warm- and cold-climate regions

为了通过热平衡分量阐明融雪过程，评估不同类型森林覆盖对融雪的影响，并估计融雪径流，在不同气候条件下的小流域和样地进行了野外观测，其中包括位于日本中部的京都大学Ashiu实验森林。日本北部的岩手县和日本最北部的北海道大学的莫希里实验森林。用两种超音速风速仪测量了感热通量的体积系数。计算潜热通量和感热通量的热量平衡法与地面积雪融化、蒸发或凝结的观测结果吻合较好，时间间隔1小时，不同区域。将太阳辐射、反照率、长波辐射、地表温度、风速、空气温度和林内相对湿度等热量平衡分量与各开阔地的热量平衡分量进行比较，并确定其差值为开阔地的比值。因此，根据气象观测资料，可以估算出不同海拔、不同坡向、不同坡度、不同森林覆盖度的不同山坡的融雪量。最后，通过这项研究工作变得非常清楚，在不同森林覆盖率和与气候条件无关的地区，融雪季节的径流过程线可以每隔一小时估算一次。

To clarify snowmelt processes by heat balance components, to evaluate effects of various types of forest coverage on snowmelt and to estimate streamflow due to snowmelt, field observations were carried out at a small watershed and at plots in the regions with different types of climate condition, where were Ashiu Experimental Forest of Kyoto University in central Japan, Mt. Iwate in northern Japan and Moshiri Experimental Forest of Hokkaido University in the most north of Japan. Bulk coefficient of sensible heat flux were measured by two types of supper sonic wind-speed meter. Consequently, heat balance method included bulk transfer equation for the estimation of latent heat flux and sensible heat flux shows a good agreement with the observed surface snowmelt, and evaporation or condensation from snow surface, at a time interval of an hour and in various regions. All of heat balance components such as solar radiation, albedo, long-wave radiation, surface temperature, wind-speed, air temperature and relative humidity inside forest were compared with these at each open plot, and its differences were determined as the rations for the values at open plot. Therefore, snowmelt at each hill slope with different altitude, different aspect, different slope angle and different type of forest coverage can be estimated from the meteorological data observed at a point. Finally, it became very clear by this research work that the hydrographs for streamflow in snowmelt season can be estimated in the areas with different forest coverages and no relation to climate condition, at a time interval of an hour.